The present invention relates to traversing with a thread guide which has to be moved over a pre-definable stroke length, in particular when the thread guide is furnished on a rotatable supported arm in the form of a rotatable supported arm respectively.
The basic principle is very old.
The arm, which can be called a xe2x80x9cpointerxe2x80x9d, was already in an earlier solution and arranged rotatable or pivotable and drivable respectively, and on the other end it was form in such a way that it could guide the thread in a controlled manner. Such an arm is known from the Swiss patent CH 153 167 and from the German patent DE-C-11 31 575. In the CH 153 167, the arm is provided on its free end with a fork-shaped slot for guiding a thread and on the other end it is rotatably supported. The drive is accomplished through a mechanical driving connection derived from the drive of the bobbin. The thread is guided over a guide rod, whereat the geometry of the arrangement of fixed guide rod, in relation to the increasing diameter of the packing during bobbin travel, is supposed to lead to a stroke reduction. The device is not suitable for the application in a modern winder.
The fork-shaped slot is of such a preset length, in that a thread within the preset length of the fork-shaped slot, based on the position of a guiding template and with the increasing bobbin, is steadily moved deeper into the fork-shaped slot, whereat a stroke reduction of the traversing thread results, actually for the reason of the reduction of the distance between the swivel axis of the lever and the position in which the thread is being guided within the fork-shaped slot, in order to obtain cone-shaped bobbin end portions. By means of a cam disk and a lever being furnished with a feeler roller, which drive the thread guide lever via a connection rod, the movement of the arm is accelerated or decelerated respectively, towards the end portions of the bobbin. EP-B453 622 suggests a device with a thread guide and a thread guide carrier, whereat the carrier is guided in a groove. The device also comprises a drive motor and a programmable control means whereat the motor is operated with a higher current than the nominal current, while the thread guide is near a reversing point, and is operated with a current below the nominal current, while the thread guide is in the remaining zone. Basic programs for different winding sections are stored in the control means. Within the control means, the calculation of the paths, the speeds and accelerations take place for the motor movement based on the angular laws being applied. Parameters which can be stored comprise the basic stroke and the variations of the basic stoke in order to produce soft bobbin edges.
According to an exemplified embodiment being illustrated, a stepping motor operates as a drive motor between the stroke centre and a reversing point against the force of a torsion spring. Near the reversing point, the constant of the spring is increased, the power supply to the stepping motor is increased and the frequency of its control impulses is reduced. Thus it is to be stopped at its reversing point. Respective monitoring means are not provided. In the stroke centre, a detector is provided which allows the detection of possible faults at this point within the traversing stroke. A traversing stroke is always controlled from this point by means of an impulse sequence. The exact definition of the reversing points cannot be derived from the description and is most likely also not possible, since they will result from the opposing forces of the motors and the spring.
In FIG. 4 of the EP-B-556 212 (WO 92 086 64) a traversing with a thread guide at the free end of a rotatable support arm is shown. According to the main claim, the description relates to a method according to which the packing formation takes place by controlling the relation between the rotation of the winding and the speed of shifting of the thread. This is to be accomplished by an arrangement for return movement which controls the rotation of the winding. The description emphasizes the controlling of the speed of the thread shifting during a single stroke movement. Nothing is, however, mentioned about the definition of the reversing points of said movement.
From the EP-0 838 422A1 a finger- or pointer-shaped, thread guide is known which at one end is arranged drivable on a motor and which on its other end is provided with a slot to guide thread. The motor is controlled by way of a pre-programmed control means for pivoting of the pointer and thus for the traversing of the thread and the pivoting movement of the pointer is continuously monitored by means of a photo-electronic detector, whereat in case of deviations from a given motion program the pivoting movement is corrected. The detector responds to detectable markings.
In order to assist the deceleration and the acceleration of the pointer at the stroke ends, there are for instance energy storage means provided in the form of springs, on an also pivotable and drivable support, which are energized during deceleration of the pointer and which are being de-energized during acceleration of the pointer. The support is pivotable by means of a drive and the drive is controlled by way of a control means in such a way that the position of the energy storage means can be changed so that on one side the energy storage means can adapt itself to the stork to be applied, for instance for the formation of the bobbin.
The traversing according to EP-A-838 422 is designed for the laying of a thread which is being drawn off a supply bobbin. From this, a precision winding is to be formed. The photo-electronic detector that monitors the position of the pointer, relates its monitoring always to a start position of the thread guide, preferably to the zero-point of its pivoting movement. This pivoting movement takes place in that the thread guide first is moved to one and then to the other reversing point, whereby the detector counts the number of markings corresponding with the stroke and from which it calculates the zero-point. In the EP-A-838 422 it is not explained in which way the reversing points are determined. The stroke of the thread guide is defined by the stroke of the pivoting movement of the above mentioned carrier and the latter stroke is monitored by a second detector. The coordination of the movements of the carrier and the pointer is mentioned, however it is not explained. According to the description, the adjustability of the energy storage means serves in any case the purpose to enable a xe2x80x9csimple changexe2x80x9d of the stroke of the thread guide. For this, the arrangement of the energy storage means on the oscillating drivable carrier is to enable a change of the stroke of the thread guide by a mere change of the stroke of the carrier and without mechanical adjustment of the position of the energy storage means.
It is to be assumed that the positions of the reversing points relate to the positions of the energy storage means. The positions of the energy storage means can be influenced by way of the control means. The application DE-A-196 23 771 discloses a traversing with at least one guiding rod (FIGS. 1/2) and if applicable two guiding rods (FIG. 3/4) for the thread guide. In a variant (FIG. 1/2) the guiding rod can be formed as the stator of a linear servo motor, for which it can be furnished with magnets. In the other variant, a pivot arm is provided in order to transmit the traversing movement onto the thread guide, for which a xe2x80x9cpivotable connectionxe2x80x9d is required between the pivot arm and the thread guide. The application DE-A-196 23 771 does not disclose anything about the definition of the reversing points. Neither does the application disclose how the servo motor is to operate.
The JP 7-165368 shows a traversing with a xe2x80x9clinear motorxe2x80x9d. The structure of this motor or the way respectively, how it is supposed to cooperate with the thread guide, cannot be recognized from the description or seen in the illustration respectively.
The JP 7-138935 describes a linear motor, wherefrom a carriage (with a thread guide) runs back and forth along a rod, whereat the magnetic field is led through the rod. Springs are being provided at the reversing points.
JP 7-137934 describes a similar arrangement whereat the springs are being replaced by detectors which cooperate with a time controller in order to initiate the reverse movement.
The structure of the linear motor cannot be clearly recognized from the latter disclosure.
It is an object of the invention to eliminate disadvantages of the state of the art. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
The task is solved in that the drive for the arm (pointer) or its support means respectively is provided with a programmable control means and that the reversing points for the stroke motion can be defined within the control means. The definition could take place by direct input of the reversing points. Preferably, however, bobbin parameters are entered from which the control means can derive the reversing points according to their programming cycle. The arrangement is defined in such a way that the controlled drive can assure the reversing at a selected reversing point. The compliance with the required reversing accuracy can be monitored by suitable detecting means and be transmitted to the control means. Approaching and moving away from a reversing point can be monitored in particular in order to recognize faults at these points. The reversing points of the arm correspond with the reversing points of the support means can thus be laid out in such a way that the oscillating movement of the thread guide provided on the arm.
The arm is being laid out with regard to form and weight in such a way, in that the motor driving the arm for a preset bobbin formation, can be accelerated and decelerated according to the preset control program. In a first preferred type of embodiment the arm is formed according to an at least first order polynom and preferably according to a second order polynom, in order to obtain a linear increasing course of the mass moment of inertia throughout the distance from the rotating axis towards the end of the pointer.
In a preferred embodiment, the cross section of the arm is of a larger dimension in the running direction than it is at a right angle to it. It is also preferred to furnish a hollow cross section over at least a preset longitudinal section of the arm and it is further preferred to fill the hollow section with filling material whose specific gravity is lower than the one of the walls of the hollow section.
It is further of advantage if the arm consists of several parts, in that preferably at the thread guiding end of the arm a thread guiding element is either inserted or otherwise attached to the arm.
Furthermore it is of advantage to manufacture the arm at least partially of carbon fiber composite material. Beyond that, it is preferred to divide the arm into a supporting part and a part at which a thread guiding part is provided. The supporting part can be manufactured as a sandwich type or as hollow profile part, whereat also an (outer) shell of the supporting part can be assembled from separately formed elements.
Due to the favorable design of the arm and the drive, a possible application of said arm exists in the circumstance, in that the arm can lay the thread within the stroke zone with a variable stroke length and outside the stroke zone it can fulfil specific functions, for instance the function of drawing-in and the bobbin replacement, in that the arm can be positioned outside the stroke zone in such a way that the arm can be stopped at one position for the catching of the thread in a catching slot or a catching knife on the bobbin tube or bobbin arbour and for the formation of a reserve bunch on a bobbin tube end. Furthermore the arm can also be stopped within the stroke zone for the formation of an end build-up on the finished bobbin.
The oscillating rotating movement of the holding means includes preferably a predetermined turning angle of between 45xc2x0 and 90xc2x0, for instance 60xc2x0. The length of the arm can be selected in dependence of the desired stroke width.
In the following the invention is being further explained in more detail by way of the exemplified embodiments in the accompanying drawing; wherein show: